CN111244887A - Protection circuit and surge detection method - Google Patents
Protection circuit and surge detection method Download PDFInfo
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- CN111244887A CN111244887A CN202010145546.1A CN202010145546A CN111244887A CN 111244887 A CN111244887 A CN 111244887A CN 202010145546 A CN202010145546 A CN 202010145546A CN 111244887 A CN111244887 A CN 111244887A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
- G01R19/1658—AC voltage or recurrent signals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
- G01R31/42—AC power supplies
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
Abstract
The invention relates to the technical field of induction cookers, and discloses a protection circuit and a surge detection method. The protection circuit comprises a rectification circuit and a control circuit, wherein the rectification circuit is used for converting an alternating current signal input by an external alternating current power supply into a direct current signal; the first voltage division circuit is connected with the output end of the rectifying circuit and is used for dividing the direct current signal; and the control circuit is connected with the first voltage division circuit and used for sampling the divided direct current electric signal, acquiring a voltage signal of the direct current electric signal and judging whether a surge signal occurs according to the voltage signal. And analyzing the direct current signal through a control circuit to obtain a voltage signal of the direct current signal, obtaining power supply voltage according to the voltage signal and judging whether a surge signal occurs. The voltage surge detection circuit and the voltage detection circuit do not need to be designed in the circuit, and the voltage surge detection circuit, the voltage detection circuit and the LC oscillating circuit are three-in-one, so that the circuit is simplified, and the production cost is saved.
Description
Technical Field
The invention relates to the technical field of induction cookers, in particular to a protection circuit and a surge detection method.
Background
In an induction cooker circuit, when an input power supply is abnormal, an IGBT (insulated gate bipolar transistor) is easily damaged due to strong interference of the power supply, so that the induction cooker circuit is abnormal. At present, in order to prevent the damage caused by abnormal power supply, a power supply voltage detection circuit and a surge detection circuit are often designed in an induction cooker circuit, whether a power supply is abnormal or not is judged according to a detected power supply voltage signal and a detected surge signal, and the induction cooker is protected. However, when the surge signal is detected by using the power supply voltage detection and surge detection circuit, the induction cooker circuit is relatively complicated, and the number of used components is large, which results in high production cost.
Disclosure of Invention
Therefore, it is necessary to provide a protection circuit and a surge detection method for solving the problems of relatively complicated circuit of the induction cooker and high production cost caused by many used elements.
A protection circuit is characterized by comprising a rectifying circuit, wherein the input end of the rectifying circuit is connected with an external alternating current power supply and is used for converting an alternating current signal into a direct current signal; the first voltage division circuit is connected with the output end of the rectifying circuit and is used for dividing the direct current signal; and the control circuit is connected with the first voltage division circuit and used for sampling and analyzing the divided direct current signal, acquiring a voltage signal of the direct current signal, judging whether a surge signal occurs according to the voltage signal, and calculating according to the voltage signal to acquire an alternating current signal.
The protection circuit divides the direct current signal output by the rectification circuit through the first voltage dividing circuit, the control circuit collects the divided direct current signal in real time, analyzes and obtains the voltage signal of the direct current signal, and judges whether the surge signal occurs in the electric signal input by the external alternating current power supply according to the voltage signal. Meanwhile, the control circuit can calculate and obtain an alternating current signal according to the voltage signal so as to collect the input voltage of the external alternating current power supply in real time. By using the protection circuit provided by the invention, the rectified direct current signal is sampled, and the direct current signal is analyzed by using the control circuit so as to realize the detection of the surge signal and the real-time acquisition of the voltage of the external alternating current power supply. The protection circuit provided by the invention can realize the detection of the surge signal and the real-time acquisition of the voltage of the external alternating current power supply without arranging a surge detection circuit and a voltage detection circuit. The electric signal at a resonance comparison point in the resonance circuit in the induction cooker circuit is collected, the control circuit is utilized to analyze according to the collected electric signal so as to judge whether a surge signal appears and obtain the real-time voltage of an external alternating current power supply, and meanwhile, the LC oscillation function can be still realized, namely, the circuit composition is simplified under the condition that the original function is not influenced, so that the circuit element composition is reduced, and the production cost is saved.
In one embodiment, the control circuit is further configured to output a control signal according to the surge signal; the protection circuit also comprises a resonant circuit, at least one electronic switching tube and a control circuit, wherein the resonant circuit is connected with the rectifying circuit and is used for converting the direct current signal into oscillation pulses with preset frequency; the emitting electrode of the electronic switching tube is grounded, and the grid electrode of the electronic switching tube is connected with the electronic switching tube driving circuit; and the electronic switching tube driving circuit is respectively connected with the resonant circuit and the control circuit and is used for driving or switching off the electronic switching tube according to the control signal output by the control circuit so as to control the on-off of the resonant circuit.
In one embodiment, the resonant circuit comprises a first capacitor, a second capacitor and a coil panel, wherein one end of the first capacitor is connected with the positive output end of the rectifying circuit, and the other end of the first capacitor is grounded; one end of the second capacitor is connected with the positive electrode output end of the rectifying circuit, and the other end of the second capacitor is connected with the collector electrode of the electronic switching tube; one end of the coil panel is connected with the positive electrode output end of the rectifying circuit, and the other end of the coil panel is connected with the collector electrode of the electronic switch tube.
In one embodiment, the rectifier circuit includes a rectifier bridge, a positive input end of the rectifier bridge is connected to a positive electrode of an external ac power supply, a negative input end of the rectifier bridge is connected to a negative electrode of the external ac power supply, a positive output end of the rectifier bridge is respectively connected to an input end of the first voltage dividing circuit and an input end of the resonant circuit, and a negative output end of the rectifier bridge is grounded.
In one embodiment, the first voltage dividing circuit includes a plurality of serially connected voltage dividing resistors for dividing the dc signal; the plurality of voltage dividing resistors are connected in series between the input terminal of the resonance circuit and the input terminal of the control circuit.
In one embodiment, the control circuit includes a main controller, connected to the first voltage dividing circuit, and configured to sample the dc signal, analyze the dc signal to obtain a power voltage and a voltage signal, determine whether a surge signal occurs according to the voltage signal, and output a control signal.
In one embodiment, the protection circuit further includes a second voltage dividing circuit, an input terminal of the second voltage dividing circuit is connected to one end of the coil panel and a collector of the electronic switch tube, respectively, and an output terminal of the second voltage dividing circuit is connected to an input terminal of the control circuit, and is configured to divide the output electrical signal of the coil panel; the control circuit is further configured to output a driving signal of the electronic switching tube according to the electrical signal at the output end of the first voltage dividing circuit and the electrical signal at the output end of the second voltage dividing circuit.
A surge detection method is applied to a protection circuit, the protection circuit comprises a rectification circuit, the surge detection method comprises the steps of carrying out voltage division processing on a direct current signal output by the rectification circuit, and sampling and obtaining the direct current signal after voltage division; analyzing the direct current signal to obtain a voltage signal of the direct current signal; and judging whether a surge signal appears according to the voltage signal, and calculating according to the voltage signal to obtain an alternating current signal.
In one embodiment, the protection circuit further comprises an electronic switching tube driving circuit, and the surge detection method further comprises comparing the direct current electrical signal with a preset electrical signal; if the direct current signal is larger than the preset electric signal, judging that a surge signal occurs; if the direct current signal is smaller than the preset electric signal, acquiring a safety pulse signal range corresponding to the direct current signal according to a preset comparison table; and acquiring a pulse signal output by the electronic switching tube driving circuit, comparing the range of the pulse signal with the range of the safety pulse signal, and judging whether a surge signal appears.
In one embodiment, the protection circuit further comprises a resonant circuit, the resonant circuit comprises at least one electronic switching tube, and the surge detection method further comprises controlling to turn off a pulse signal output to the electronic switching tube driving circuit when a surge signal occurs so as to turn off the electronic switching tube and break a path of the resonant circuit.
In one embodiment, the surge detection method further includes determining that the surge signal disappears when the voltage signal is smaller than a preset threshold within a preset time, waiting for the preset time, and controlling to output a pulse signal to the electronic switching tube driving circuit to drive the electronic switching tube to normally operate in the resonant circuit.
Drawings
FIG. 1 is a block diagram of a protection circuit according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a protection circuit according to an embodiment of the present invention;
fig. 3 is a flow chart of a method of detecting a surge according to an embodiment of the present invention;
fig. 4 is a flow chart of another surge detection method according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The electromagnetic oven circuit adopts the heating principle of magnetic field induction current (also called eddy current), and the rectifying circuit converts the external alternating current signal into a direct current signal, and then the direct current signal is converted into a high-frequency alternating current signal by the resonance circuit. An alternating magnetic field of the high-frequency induction cooker is formed through the magnetic induction coil. When the magnetic lines of force in the magnetic field pass through the bottom of the ferromagnetic material vessel, an alternating circuit, i.e. an eddy current, is generated inside the vessel. The eddy current makes the iron molecules of the pot move irregularly at high speed, and the molecules collide and rub with each other to generate heat energy to make the pot self generate heat at high speed, so that the pot can achieve the purpose of heating and cooking food.
An IGBT (insulated gate bipolar transistor) is one of the most important devices in an induction cooker circuit, and is used in a resonant circuit in cooperation with a magnetic induction coil to generate a high-frequency alternating magnetic field. However, the IGBT is easily damaged by strong interference from the power supply, which causes an abnormality in the circuit of the induction cooker. The surge is an instantaneous sudden change of a normal working voltage, and mainly refers to a strong pulse generated by the instantaneous sudden change of a power supply in electronic design, and a very large sudden change can be superposed on the working voltage, so that the IGBT is damaged. Therefore, the surge signal needs to be detected to determine whether the external power supply is abnormal, and the circuit of the induction cooker is protected.
Fig. 1 is a block diagram of a protection circuit according to an embodiment of the present invention, in which the protection circuit includes at least a rectifier circuit 100, a first voltage divider circuit 200, and a control circuit 300. The input end of the rectifier circuit 100 is connected to an external ac power supply, and is configured to convert an ac signal input by the external ac power supply into a dc signal. The first voltage dividing circuit 200 is connected to an output end of the rectifying circuit 100, and is configured to divide the dc voltage signal. The control circuit 300 is connected to the first voltage dividing circuit, and is configured to sample and analyze the divided dc electrical signal, obtain a voltage signal of the dc electrical signal, and determine whether a surge signal occurs according to the voltage signal. Meanwhile, the control circuit 300 may further analyze the voltage signal to obtain an ac signal of an external ac power source. The rectifier circuit 100 is further connected to the control circuit 300, and is configured to provide an electrical signal required for operation to the control circuit 300.
In the protection circuit according to the embodiment of the present invention, an ac electrical signal input from an external power supply is rectified by the rectifier circuit 100, and a dc electrical signal is output. The first voltage dividing circuit 200 divides the dc signal, and divides the dc signal into a sampling range of the control circuit 300, so that the control circuit 300 can sample the dc signal in real time. The control circuit 300 samples and obtains the divided direct current signal in real time, and analyzes and obtains a voltage signal of the direct current signal. In this embodiment, the voltage signal includes a voltage increase rate. The control circuit can judge whether the surge signal occurs through the voltage increase rate. For example, when the instantaneous voltage increase rate of the dc electrical signal exceeds the normal voltage fluctuation range, indicating that the electrical signal input by the external ac power supply has a tendency of instantaneous large increase, the control circuit 300 determines that a surge signal occurs. The protection circuit provided by the invention realizes the functions of judging the surge signal and collecting the voltage of the external alternating current power supply through the first voltage division circuit 200 and the control circuit 300 without additionally utilizing a surge signal detection circuit and a voltage detection circuit in front of a rectification circuit, thereby simplifying the circuit design of the induction cooker circuit and reducing the production cost of products.
In one embodiment, the protection circuit further comprises a resonant circuit 400 and an electronic switching tube driving circuit 500. The resonant circuit 400 at least comprises an electronic switching tube, and the resonant circuit 400 is connected with the rectifying circuit 300 and is used for converting the direct current signal into a high-frequency oscillation pulse. The emitter of the electronic switch tube is grounded, and the gate of the electronic switch is connected with the electronic switch tube driving circuit 500. The control circuit 300 is further configured to output a control signal to the electronic switching tube driving circuit 500 according to the surge signal, and is respectively connected to the resonant circuit 400 and the control circuit, and configured to drive or turn off the electronic switching tube according to the control signal output by the control circuit to control on/off of the resonant circuit. In this embodiment, the electronic switch is an IGBT (insulated gate bipolar transistor). The induction cooker circuit converts a direct current electrical signal into a high frequency alternating current electrical signal through the resonance circuit 400. And then, an alternating magnetic field of the high-frequency induction cooker is formed through the magnetic induction coil in the resonant circuit 400, so that the cooker is heated.
Fig. 2 is a schematic circuit diagram of a protection circuit according to an embodiment of the present invention, in which the resonant circuit 400 includes a first capacitor (corresponding to C5 in the figure), a second capacitor (corresponding to C7 in the figure), and a coil (corresponding to coil 1 in the figure), one end of the first capacitor C5 is connected to the positive output terminal of the rectifier circuit 100, and the other end of the first capacitor C5 is grounded. One end of the second capacitor C7 is connected to the positive output end of the rectifier circuit 100, and the other end of the second capacitor C7 is connected to the collector of an electronic switching tube (corresponding to the IGBT1 in the figure). The coil panel 1 is connected in parallel with the second capacitor C7, one end of the coil panel 1 is connected with the positive output end of the rectifying circuit 100, and the other end of the coil panel 1 is connected with the collector of an electronic switching tube (corresponding to the IGBT1 in the figure). The collector of the electronic switch tube IGBT1 is connected to the second capacitor C7 and the coil panel 1, respectively, the emitter of the electronic switch tube IGBT1 is grounded, and the gate of the electronic switch tube IGBT1 is connected to the electronic switch tube driving circuit 500.
Specifically, the gate of the electronic switching tube IGBT1 receives a rectangular pulse drive from the drive circuit output. When the electronic switching tube IGBT1 is turned on, the current flowing through the coil disk 1 increases rapidly; when the electronic switch tube IGBT1 is turned off, the coil panel 1 and the second capacitor C7 generate a resonant current, and the electronic switch tube IGBT1 generates a high voltage positive pulse. The process is repeated, the resonance current is oscillated between the coil panel 1 and the second capacitor C7 by the on and off of the electronic switch tube IGBT1, the coil panel 1 outputs high-frequency electromagnetic energy to the cookware, and eddy current is formed at the bottom of the iron cookware to heat the cookware.
In one embodiment, the rectifier circuit 100 includes a rectifier bridge (corresponding to BG1 in the figure), a positive input end of the rectifier bridge BG1 is connected to a positive electrode of an external ac power source, a negative input end of the rectifier bridge BG1 is connected to a negative electrode of the external ac power source, a positive output end of the rectifier bridge BG1 is connected to an input end of the first voltage dividing circuit and an input end of the resonant circuit, respectively, and a negative output end of the rectifier bridge BG1 is grounded. Specifically, alternating current signals input by a 220V external alternating current power supply are connected into the rectifier bridge BG1 through a voltage dependent resistor RZ1, a resistor R1 and an EMC component which are arranged in parallel, and the voltage dependent resistor RZ1, the resistor R1 and the EMC component which are arranged in parallel are used for protecting the induction cooker and preventing the induction cooker from being damaged due to overhigh external alternating current signals. The rectifier bridge BG1 rectifies the alternating current signal, rectifies the alternating current signal into a command electrical signal and provides electric energy for subsequent circuits.
In one embodiment, the first voltage dividing circuit 200 includes a plurality of serially connected voltage dividing resistors (R13, R14, R15, R16 in the figure) for dividing the dc signal. The plurality of voltage dividing resistors are connected in series between the input terminal of the resonance circuit 400 and the input terminal of the control circuit 300. The input direct current signal at the input end of the coil panel 1 is divided and controlled within the electric signal sampling range of the control circuit 300, so that the control circuit 300 can sample the input direct current signal of the coil panel 1. The output of the first voltage divider circuit 200 is connected to the input of the control circuit 300, and this connection point is defined as the resonance comparison point a of the coil disk 1.
In one embodiment, the control circuit 300 includes a main controller (corresponding to the main CPU in the figure) connected to the first voltage divider circuit 200. The main control CPU is used for sampling the direct current signal, analyzing and acquiring a voltage signal of the direct current signal, and analyzing and acquiring alternating current voltage of an external alternating current power supply and the voltage increase rate of the direct current signal according to the voltage signal. And the main control CPU converts the obtained direct current voltage into alternating current voltage according to an alternating current-direct current conversion formula, and then the alternating current voltage of the external alternating current power supply can be obtained. In this embodiment, the voltage signal includes a voltage increase rate of the dc signal. And meanwhile, the main control CPU judges whether a surge signal occurs according to the voltage increase rate. If the instantaneous voltage increase rate of the direct current electrical signal exceeds the normal voltage fluctuation range, indicating that the electrical signal input by the external alternating current power supply has a tendency of instantaneous large increase, the master control CPU judges that a surge signal output control signal is generated to the electronic switching tube driving circuit 500. The master control CPU turns off the pulse signal output to the electronic switching tube driving circuit 500 to turn off the electronic switching tube IGBT1 to break the path of the resonant circuit. By disconnecting the passage of the resonance circuit, the electronic switching tube IGBT1 is prevented from being damaged due to strong interference of surge signals of an external power supply, and the induction cooker is protected.
In one embodiment, the protection circuit further includes a second voltage dividing circuit 600, wherein input terminals of the second voltage dividing circuit 600 are respectively connected to one end of the coil panel 1 and a collector of the electronic switch IGBT1, and an output terminal of the second voltage dividing circuit 600 is connected to an input terminal of the control circuit, and is configured to divide the output electrical signal of the coil panel 1. The second voltage dividing circuit 600 includes a plurality of voltage dividing resistors (R21, R22, R23, R24, R25 in the figure) connected in series for dividing the high frequency electric signal output from the coil disk 1. The plurality of voltage dividing resistors are connected in series between the output terminal of the coil disk 1 and the input terminal of the control circuit 300. The high-frequency electric signal at the output end of the coil panel 1 is divided, and the high-frequency electric signal is controlled within the electric signal sampling range of the control circuit 300, so that the control circuit 300 can sample the output high-frequency electric signal of the coil panel 1. The output terminal of the second voltage divider circuit 600 is connected to the input terminal of the control circuit 300, and this connection point is defined as a resonance comparison point B of the coil disk 1.
When the induction cooker works, the electronic switching tube IGBT1 works between the cut-off state and the conducting state rapidly and alternately. When different heating powers are set, the proportion of the turn-off time to the turn-on time of the electronic switching tube IGBT1 is different. At this time, when the on and off states of the electronic switch tube IGBT1 are inconsistent with the state of the coil panel 1, if the coil panel 1 generates a high voltage and a large current is generated, the electronic switch tube IGBT1 is inevitably damaged. The control circuit 300 samples a resonance comparison point a, and a comparator in the control circuit 300 obtains an input electric signal of the coil panel 1 after voltage division at a non-inverting input end; the control circuit 300 samples a resonance comparison point B, and the inverted input end of the comparator in the control circuit 300 obtains the divided output electrical signal of the coil panel 1. The control circuit 300 and the coil panel 1 form a synchronous circuit for synchronously controlling the on/off of the electronic switching tube IGBT 1.
When the electronic switching tube IGBT1 is in saturation conduction, the voltage at the input end of the coil panel 1 is positive, the voltage at the output end of the coil panel 1 is negative, the comparator circuit in the control circuit 300 is equivalent to a pass state, and a pulse signal can pass through smoothly; when the electronic switch tube IGBT1 is turned off, the voltage at the input end of the coil panel 1 is negative, the voltage at the output end of the coil panel 1 is positive, the comparator circuit in the control circuit 300 is immediately turned over, and the output of the control circuit 300 is at a low level, which is equivalent to short-circuiting a pulse signal to the ground, thereby ensuring that the electronic switch tube IGBT1 is reliably turned off, and preventing the electronic switch tube IGBT1 from being damaged by high voltage and large current.
In one embodiment, the control circuit 300 collects and processes the electric signals at the resonance comparison point a and the resonance comparison point B to obtain a voltage signal proportional to the magnitude of the load current, which is used as a detection signal of the pot. The detection circuit inside the control circuit 300 automatically adjusts the output power according to the voltage signal. If the electromagnetism stove during operation, the condition that does not place the pan, the pan of placing is unqualified or the position of placing is incorrect appears, control circuit 300 judges that the detection voltage value does not reach the setting value, and its inside detection circuitry then judges that the kitchen face does not have the pan, control circuit 300 stops pulse signal output, electronic switch pipe IGBT1 is in the stop state stop work to play the guard action to the electromagnetism stove.
In one embodiment, the control circuit 300 may further detect the level of the input ac signal by collecting and processing the electric signal at the resonance comparison point a, so as to prevent the electronic switch tube IGBT1 and other circuit components from being damaged due to too high or too low voltage. For example, the input alternating current signal is 220V, and the normal working voltage of the induction cooker is in the range of 150V-260V. When the voltage input to the control circuit 300 at the resonance comparison point a changes, the internal circuit of the control circuit 300 determines whether the input voltage is normal according to the voltage change. When the input voltage is lower than 150V or higher than 260V, the control circuit 300 stops the output of the pulse signal, and simultaneously stops the operation of the electronic switching tube IGBT1, thereby protecting the induction cooker.
Fig. 3 is a flowchart of a method of detecting a surge according to an embodiment of the present invention, in which the method is applied to a protection circuit including a rectifier circuit 100, and the method includes the following steps S100 to S300.
S100: and carrying out voltage division processing on the direct current signal output by the rectifying circuit, and sampling to obtain the direct current signal after voltage division.
S200: and analyzing the direct current signal to obtain a voltage signal of the direct current signal.
S300: and judging whether a surge signal appears according to the voltage signal, and calculating according to the voltage signal to obtain an alternating current signal.
According to the surge detection method provided by the present invention, the dc signal rectified and output by the rectifier circuit 100 is divided by the first voltage dividing circuit 200. The control circuit 300 collects the divided dc signal in real time and analyzes the dc signal to obtain a voltage signal of the dc signal. The control circuit 300 determines whether the electrical signal input by the external ac power supply is in surge according to the voltage signal. And when the voltage signal is greater than a preset value, the surge phenomenon of the electric signal input by the external alternating current power supply is indicated. Meanwhile, an alternating current signal input by an external alternating current power supply can be obtained according to the voltage signal. By using the surge detection method provided by the invention, the detection of the surge signal is realized by sampling and analyzing the rectified direct current signal, a voltage surge detection circuit and a voltage detection circuit do not need to be additionally arranged on the front side of the rectification circuit 100, the circuit structure of the induction cooker is simplified, thereby reducing circuit elements and saving production cost.
Fig. 4 is a flow chart of another method for detecting surge according to an embodiment of the present invention, wherein in an embodiment, the method further includes the following steps S400 to S700.
S400: and comparing the direct current electric signal with a preset electric signal.
S500: and if the direct current signal is greater than the preset electric signal, judging that a surge signal occurs.
S600: and if the direct current signal is smaller than the preset electric signal, acquiring a safety pulse signal range corresponding to the direct current signal according to a preset comparison table.
S700: and acquiring a pulse signal output by the electronic switching tube driving circuit, comparing the range of the pulse signal with the range of the safety pulse signal, and judging whether a surge signal appears.
Specifically, when the comparator circuit inside the control circuit 300 is equivalent to the access state, the control circuit 300 collects the dc signal subjected to the voltage division processing by the first voltage dividing circuit 200 in real time, and compares the dc signal with a preset electric signal. And if the direct current signal is greater than the preset electric signal, judging that a surge signal occurs. And if the direct current signal is smaller than the preset electric signal, acquiring a safety pulse signal range corresponding to the direct current signal according to a preset comparison table. The control circuit 300 obtains the pulse signal output by the electronic switching tube driving circuit 500, compares the pulse signal with the safety pulse signal range, and judges whether a surge signal occurs. If the pulse signal is within the range of the safety pulse signal, judging that no surge signal occurs; otherwise, judging that a surge signal appears.
For example, the safe operating voltage range of the induction cooker is 150V-260V. And setting the preset electric signal to be 300V, wherein the peak voltage of the alternating current electric signal corresponding to the preset electric signal is 300 x 1.414-424V. When the direct current signal acquired by the control circuit 300 in real time is greater than the preset signal, the control circuit 300 determines that a surge signal occurs. Because the pulse amplitude tolerance of the electronic switching tube to pulse signals with different pulse widths is different. For example, the electronic switch tube can bear a pulse signal with the pulse amplitude of 300V and the pulse width of 5ms, but cannot bear a pulse signal with the pulse amplitude of 300V and the pulse width of 20 ms. Therefore, when determining whether or not the input power supply voltage is a surge signal that may cause damage to the electronic switching device, it is necessary to perform the surge signal determination by integrating the dc signal and the pulse signal. And when the direct current signal is smaller than the preset electric signal, acquiring a corresponding safety pulse signal range on a preset comparison table according to the direct current signal acquired in real time. The preset comparison table is obtained by a pre-experiment and comprises the safe tolerance range of the electronic switching tube to pulse signals with different pulse amplitudes and pulse widths. Meanwhile, the control circuit 300 obtains the pulse signal output by the electronic switching tube driving circuit 500. Comparing the pulse signal acquired in real time with a safety pulse signal range, and if the pulse signal is in the safety pulse signal range, judging that no surge signal occurs; otherwise, judging that a surge signal appears. In a traditional surge protection circuit of an induction cooker, if the value of a preset electric signal is set to be too high, the situation of false triggering is easy to occur; if the voltage is too low, the surge protection circuit may not be able to effectively protect the induction cooker circuit. The surge detection method for judging by comprehensively inputting the electric signal and the pulse signal improves the protection sensitivity of the protection circuit and is not easy to generate the phenomenon of false triggering.
In one embodiment, the surge detection method further includes that when a surge signal occurs, the control circuit 300 controls to turn off the pulse signal output to the electronic switching tube driving circuit 500, so that the electronic switching tube IGBT1 is stopped, and the electronic switching tube IGBT1 is prevented from being damaged by high voltage generated by transient sudden change, thereby protecting the induction cooker.
In one embodiment, the surge detection method further includes determining that the surge signal disappears when the voltage signal of the dc electrical signal is smaller than a preset threshold within a preset time. After the surge signal is judged to disappear, the control circuit 300 waits for a preset time, and after the electrical signal input by the external alternating-current power supply is determined to be recovered and stabilized, the control circuit controls to output a pulse signal to the electronic switching tube driving circuit 500. The electronic switch tube driving circuit 500 drives the electronic switch tube IGBT1 to work, and the electronic switch tube IGBT1 is turned on and off to enable the coil panel 1 in the resonant circuit 400 to output high-frequency electromagnetic energy to the cookware, so that the electromagnetic oven is restored to a normal working state.
According to the protection circuit and the surge detection method provided by the invention, an alternating current signal input by an external alternating current power supply is rectified by the rectifying circuit 100, and is output after being rectified into a direct current signal. The first voltage dividing circuit 200 divides the dc signal, so that the control circuit 300 can acquire and acquire the dc signal. The control circuit 300 acquires the dc signal in real time, and calculates a voltage signal of the dc signal. And judging whether the voltage surge occurs in the electric signal input by the external alternating current power supply according to the voltage signal. If the voltage signal exceeds the normal voltage fluctuation range, the electric signal input by the external alternating current power supply has a tendency of instantaneous great increase, namely a surge signal appears. By using the protection circuit provided by the invention, the detection of surge signals and the real-time acquisition of the voltage of an external alternating current power supply are realized by sampling and analyzing the rectified direct current signals, namely the resonance comparison point A of the coil panel 1, and meanwhile, the original LC oscillation function can be realized, a voltage surge detection circuit and a voltage detection circuit do not need to be added outside a rectifier circuit, and the voltage surge detection circuit, the voltage detection circuit and the LC oscillation circuit are combined into a whole, so that the circuit element composition is reduced, and the production cost is saved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A protection circuit, comprising:
the input end of the rectifying circuit is connected with an external alternating current power supply and is used for converting an alternating current signal into a direct current signal;
the first voltage division circuit is connected with the output end of the rectifying circuit and is used for dividing the direct current signal;
and the control circuit is connected with the first voltage division circuit and used for sampling and analyzing the divided direct current signal, acquiring a voltage signal of the direct current signal, judging whether a surge signal occurs according to the voltage signal, and calculating according to the voltage signal to acquire an alternating current signal.
2. The protection circuit of claim 1, wherein the control circuit is further configured to output a control signal according to the surge signal; wherein the protection circuit further comprises:
the resonant circuit at least comprises an electronic switching tube, is connected with the rectifying circuit and is used for converting the direct current signal into oscillation pulses with preset frequency; the emitting electrode of the electronic switching tube is grounded, and the grid electrode of the electronic switching tube is connected with the electronic switching tube driving circuit;
and the electronic switching tube driving circuit is respectively connected with the resonant circuit and the control circuit and is used for driving or switching off the electronic switching tube according to the control signal output by the control circuit so as to control the on-off of the resonant circuit.
3. The protection circuit according to claim 2, wherein the resonance circuit includes a first capacitor, a second capacitor, and a coil disk, one end of the first capacitor is connected to the positive output terminal of the rectification circuit, and the other end is grounded; one end of the second capacitor is connected with the positive electrode output end of the rectifying circuit, and the other end of the second capacitor is connected with the collector electrode of the electronic switching tube; one end of the coil panel is connected with the positive electrode output end of the rectifying circuit, and the other end of the coil panel is connected with the collector electrode of the electronic switch tube.
4. The protection circuit according to claim 2, wherein the rectifier circuit comprises a rectifier bridge, a positive input end of the rectifier bridge is connected with a positive electrode of an external alternating current power supply, a negative input end of the rectifier bridge is connected with a negative electrode of the external alternating current power supply, a positive output end of the rectifier bridge is respectively connected with an input end of the first voltage division circuit and an input end of the resonance circuit, and a negative output end of the rectifier bridge is grounded.
5. The protection circuit according to claim 2, wherein the first voltage dividing circuit includes a plurality of voltage dividing resistors connected in series for dividing the dc signal; the plurality of voltage dividing resistors are connected in series between the input terminal of the resonance circuit and the input terminal of the control circuit.
6. The protection circuit of claim 2, wherein the control circuit comprises:
and the main controller is connected with the first voltage division circuit and used for sampling and analyzing the divided direct current signal, acquiring a voltage signal of the direct current signal, judging whether a surge signal appears according to the voltage signal, outputting a control signal and calculating according to the voltage signal to acquire an alternating current signal.
7. The protection circuit of claim 3, further comprising:
the input end of the second voltage division circuit is respectively connected with one end of the coil panel and the collector of the electronic switch tube, and the output end of the second voltage division circuit is connected with the input end of the control circuit and is used for dividing the output electric signal of the coil panel;
the control circuit is further configured to output a driving signal of the electronic switching tube according to the electrical signal at the output end of the first voltage dividing circuit and the electrical signal at the output end of the second voltage dividing circuit.
8. A surge detection method is applied to a protection circuit, the protection circuit comprises a rectification circuit, and the surge detection method comprises the following steps:
dividing the voltage of the direct current signal output by the rectifying circuit, and sampling to obtain the divided direct current signal;
analyzing the direct current signal to obtain a voltage signal of the direct current signal;
and judging whether a surge signal appears according to the voltage signal, and calculating according to the voltage signal to obtain an alternating current signal.
9. The surge detection method of claim 8, wherein the protection circuit further comprises an electronic switching tube drive circuit, the surge detection method further comprising:
comparing the direct current electric signal with a preset electric signal;
if the direct current signal is larger than the preset electric signal, judging that a surge signal occurs;
if the direct current signal is smaller than the preset electric signal, acquiring a safety pulse signal range corresponding to the direct current signal according to a preset comparison table;
and acquiring a pulse signal output by the electronic switching tube driving circuit, comparing the range of the pulse signal with the range of the safety pulse signal, and judging whether a surge signal appears.
10. The surge detection method of claim 9, wherein the protection circuit further comprises a resonant circuit including at least one electronic switching tube, the surge detection method further comprising:
when a surge signal occurs, the pulse signal output to the electronic switching tube driving circuit is controlled to be turned off so as to turn off the electronic switching tube and break the passage of the resonance circuit.
11. The surge detection method of claim 10, further comprising:
when the voltage signals are all smaller than a preset threshold value within a preset time, judging that the surge signals disappear, waiting for the preset time, and controlling to output pulse signals to the electronic switching tube driving circuit so as to drive the electronic switching tube to normally work in the resonance circuit.
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| CN202010145546.1A CN111244887A (en) | 2020-03-05 | 2020-03-05 | Protection circuit and surge detection method |
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| CN202010145546.1A CN111244887A (en) | 2020-03-05 | 2020-03-05 | Protection circuit and surge detection method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113687133A (en) * | 2021-08-19 | 2021-11-23 | 华为技术有限公司 | Surge detection circuit and detection device for active protection |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102711298A (en) * | 2012-05-23 | 2012-10-03 | 美的集团有限公司 | Heating control device and control method for induction cooker |
| CN206060516U (en) * | 2016-08-29 | 2017-03-29 | 佛山市顺德区美的电热电器制造有限公司 | A kind of current sampling circuit and surge protection circuit |
| CN107528289A (en) * | 2016-06-20 | 2017-12-29 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and its protection device |
| CN108966393A (en) * | 2017-05-19 | 2018-12-07 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating circuit and electromagnetic heating circuit surge protection method |
-
2020
- 2020-03-05 CN CN202010145546.1A patent/CN111244887A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102711298A (en) * | 2012-05-23 | 2012-10-03 | 美的集团有限公司 | Heating control device and control method for induction cooker |
| CN107528289A (en) * | 2016-06-20 | 2017-12-29 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and its protection device |
| CN206060516U (en) * | 2016-08-29 | 2017-03-29 | 佛山市顺德区美的电热电器制造有限公司 | A kind of current sampling circuit and surge protection circuit |
| CN108966393A (en) * | 2017-05-19 | 2018-12-07 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating circuit and electromagnetic heating circuit surge protection method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113687133A (en) * | 2021-08-19 | 2021-11-23 | 华为技术有限公司 | Surge detection circuit and detection device for active protection |
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